Compared with spherical and quadric surfaces, aspheric surfaces have more degrees of design freedom. If aspheric surfaces are used in off-axis three-mirror optical systems, the aberrations of the off-axis three-mirror optical systems can be significantly reduced, while the freedom of the off-axis three-mirror optical systems can be greatly improved.
However, conventional methods for designing off-axis aspheric optical system have limitations in the number of fields of view and the number of apertures to be considered.